The invention relates to a unit mount, in particular for a motor vehicle, and to a method for mounting such a unit mount according to the independent claims.
Many different configurations of unit mounts for motor vehicles are known. By way of unit mounts, components such as, for example, an internal combustion engine, a gear selector transmission or a motor-transmission unit can be connected to a vehicle body or to an axle carrier, which is also referred to as a subframe, in a vibration-damping manner. For this purpose, such unit mounts have a support arm which is rigidly attached to the unit to be damped and engages in a housing which is rigidly connected to the vehicle body and which surrounds the end of the support arm facing away from the unit. This end section of the support arm arranged in the housing and the housing itself do not touch directly, but are separated from each other by a vibration-damping elastomeric material that is arranged between the two components. The elastomeric material, in conjunction with corresponding stop faces disposed on the inner sides of the housing, not only dampens vibrations, but also limits movement amplitudes of the unit to be damped. For the vibration-damping absorption of the vertically acting weighting force of the unit, which is introduced into the housing via the support arm, unit mounts have frequently an elastomeric support spring arranged inside the housing in addition to the abovementioned elastomeric material, which is essentially designed as a cube or as a cuboid and supports the end section of the support arm disposed inside the housing. The support arm usually extends in a transverse direction of the vehicle. In a motor vehicle, unit mounts are frequently arranged in pairs as a support unit, wherein a first of the two unit mounts is designed as a so-called fixed bearing and the other unit mount is designed as a so-called floating bearing. The housing of such a fixed bearing provides stop faces for the end section of the support arm arranged in the housing in the transverse direction of the vehicle, a vertical direction of the vehicle, and a longitudinal direction of the vehicle having a positive orientation that generally corresponds to a direction of travel. In order to be able to accommodate a thermal expansion of the unit to be damped, a second bearing of such a bearing unit is often designed as a floating bearing, which essentially constructed similar to the fixed bearing. However, unlike the abovementioned fixed bearing, the floating bearing permits movements in one of the previously mentioned three directions. This is generally the transverse direction of the vehicle, whereby movements in this direction can take place both in a positive as well as in a negative orientation.
DE 10 2010 043 165 A1 discloses a unit mount designed as a fixed bearing with a one-piece, but not an integral, sheet metal housing, wherein the sheet metal housing consists of two housing parts which are joined by welding or soldering. The two housing parts are joined to form a one-piece sheet metal housing before the elastomeric support spring is inserted and the support arm is mounted. The sheet metal housing has, in three mutually orthogonal directions, in each case pairwise bump stops formed as stop faces in order to limit the movement of the support arm relative to the sheet metal housing when the load is subjected to vibrations, with the limitation being provided for movements having both a positive orientation and a negative orientation with respect to the respective extension direction. The sheet metal housing also has a sword-shaped tongue, which is formed by an edge of a wall section of the sheet metal housing protruding into the interior of the sheet metal housing. The movement is limited in one of the extension directions in that the tongue engages in a groove of the support arm coated with elastomer material and thus constitutes a wall-like boundary in the form of a stop face. For assembling the unit mount, the elastomeric support spring is first inserted into the housing and the support arm is thereafter mounted. For this purpose, an end section of the support arm having the aforementioned groove is forced into the sheet metal housing around the tongue. A resistance must hereby be overcome which results from the compression of the elastomeric support spring when the support arm is forced in.
It is an object of the invention to provide a cost-effective and, at the same time, lighter unit mount which is easier to assemble and saves material.